Now it's worth mentioning that I have an old 50MM 1.4 lense from
an old F2 nikon.
It is a factor here. I alredy tried it on nikon D90, didn't work.
any of those could mount this lense? if not what can?
or should I ditch it altogether?

Almost forgot ,areas of intrest in phogtography is : Everything!
from people to events (concerts and such) to views to wild life, I like them all.
I like photography in general. but from the FZ 40 I learned that I need:
Good night capability, and speed.

The D7000 is an excellent camera. Why not visit your nearest camera shop & ask them to mount your lens. It will also give you the chance to hold & get to try the others you have mentioned. (you don't HAVE to purchase from them if you've seen better prices)

But is the diffrence bewteen the 5100 and the 7000 really that big that
it's worth the price diffrence? They do have the same sensor and processor don't they?

The lens didn't fit on a D90 , I'm not sure what to do with it , it is good.
And now to concider the 7D and a77 that just ads to my confusion.

a77 ,D7 ,60D ,5100 ,7000 , I don't know what to pick..

I tried visiting a shop and asked them but they wouldn't agree to let me try.
I'll try another one. but it seems like you have one and I can see your happy with it , would it be rude of me to ask you if you could show me some of your work?

With a body, you should bear in mind that the sensor isn't the only consideration. There are other feature sets that you may require, which are only present in the D7000. The superior AF and continuous shooting rate would be extremely handy for shooting fast-moving subjects so if your subject matter requires such feature sets, perhaps it is worth paying the premium otherwise if you don't think you'll make enough use of the superior features to justify the premium, perhaps it's only worth going with the D5100.

I see.
Well actually, as I mentioned speed is important to me.
But there is one thing that's niggling me about the D7000.

I watched and read the reviews about it , (in here as well)
And they said that the buffer in it is small, which means that yes it
can shoot like a machine gun, but only for a short amount of time.
a maximum of 10 - 25 shots if i'm not mistaking.

which is why I still consider the other opponents, such as the 60D or 7D.
maybe I should wait for D7100?

Err.. It's almost Christmas therefore most members here are likely to be spending time with their families or doing last minute shopping i.e. they're probably going to spend less time at their computers, assuming that they have access. Maybe that's food for thought?

If build quality isnt a huge concern for you, I would recomend the D60 as it is slightly cheaper than the D7000. There are no issues with buffer UNLESS you shoot RAW + jpeg and RAW. Otherwise, happy snapping.

I can recomend the 7D but imo, its in another category from the D7000. If you want to save your money and dont really mind the plasticy build quality, the 60D is imo the best compromise for you atm.

I guess, night clubs , concerts
all kingds of diffrent events.
For exsample, I'm going to a RHCP concert in july
and since I don't know if i'll ever be in thire concert ever agin I would like
to capture this.

Also In the next year or so , I'm going to travel a lot.
Form Finland to Italy to France , to Thailand...
I would like to cherish those as well , and the fact that the night comes,
should not stop me snaping those memories.

In that case, it sounds like using a tripod/monopod isn't practical so a lens with a wide aperture may suit you best e.g. f/2.8 or better. The focal range will naturally depend on how for away or close you are to the subject though your examples will likely call for wider angle lenses.

Are you absolutely sure your 50mm f/1.4 doesn't work on the D90? Like Jiko said, it ought to work as it's the same type of lens mount (however I am far more familiar with Canon hardware than Nikon) and that lens should work well in low lighting conditions though it has the disadvantage of a fixed focal length.

One word of warning, you should always check if DSLRs are permitted when you go to clubs or concerts. It is quite often the case that the management of such events assumes that you're a professional photographer trying to make a buck out of them without their consent and therefore they may refuse to let you take the camera in. They will almost certainly take exception to you bringing a DSLR to a club where there is a photographer who takes photos of a group party and offers to sell the photos to the group.

EDIT: It looks like Leo's had the same experience as me and a few friends of mine!